Some printing systems use a heated drum or roller system to form an image on a target media, such as paper. In an offset solid ink printing process, a heated drum receives ink ejected from a printhead and transfers the image to media. These heated roller systems regulate the surface temperature of the roll to maintain the ink in a viscoelastic state. Ink in this state is better able to spread and penetrate into the target media during transfer. Such a process can improve the ultimate print quality by, for example, increasing solid fill density, decreasing ink layer thickness, and increasing the durability of the prints.
Previously known drum heaters used in solid ink-jet printers include external quartz halogen lamps that are mounted in reflector assemblies. More recently, an internal mica/wire based drum heater has been used for drum heating, as described in U.S. Patent Application US2007/0045295A1 issued to Hays et al. (hereinafter ‘the 295 application’), and in U.S. Pat. No. 6,713,728 issued to Justice et al. (hereinafter ‘the 728 patent’), the disclosures of which are expressly incorporated herein by reference in their entireties. The heater disclosed in the '295 application is more efficient because it includes an open-ended enclosure mounted about the heating elements of the heater so only a small gap exists between the perimeter of the enclosure face and the circumferential interior surface of the drum as it rotates past the heater. The structure of the heater in the '295 application helps reduce convective heat losses. Because the heating of the drum surface is more efficient, however, more accurate temperature control methods would be useful for optimum printing quality.